initials vs moniker

initials

noun
  • An abbreviation of a person's name, constructed by taking the initial letters of first, last, and sometimes middle name(s). See monogram 

moniker

noun
  • A personal name or nickname; an informal label, often drawing attention to a particular attribute. 

  • A person's signature. 

  • An object (structured item of data) used to associate the name of an object with its location. 

How often have the words initials and moniker occurred in a corpus of books? (source: Google Ngram Viewer )